What's the Difference Between Dry and Wet Age-Related Macular Degeneration?

Vanessa Caceres

The differences between dry age-related macular degeneration and wet age-related macular degeneration can be confusing, but they're important to know. They could mean the difference between a doctor simply monitoring your disease or needing regular injections to stop rapid vision loss.

Age-related macular degeneration is very common with aging, and the chance of developing it increases with each decade after age 50. If you've been diagnosed with age-related macular degeneration, you're not alone. There are 11 million people in the U.S. with age-related macular degeneration, according to the BrightFocus Foundation, a nonprofit group that supports research and education about eye and brain diseases. Age-related macular degeneration will affect an estimated 196 million people around the world by 2020.

Age-related macular degeneration affects vision in the central part of the eye. It can make it hard to do important daily tasks like reading, driving and seeing faces, according to Dr. Rahul Khurana, an American Academy of Ophthalmology spokesperson who practices at Northern California Retina Vitreous Associates in Daly City, California.

Our eyes have a retina, a thin layer of tissue in the back of the eye that helps us to sense light and send images of what we're seeing to the brain. The macula, which is part of the retina, gives us that central vision. With age-related macular degeneration, the macula doesn't work like it should. As the disease progresses, it affects vision.

Age-related macular degeneration is caused by a complex mix of our genetics and lifestyle, such as whether or not you smoke, says Dr. Philip J. Rosenfeld, a professor of ophthalmology at Bascom Palmer Eye Institute in Miami. Aging also is part of the cause -- specifically being age 50 or older.

There are two different types of age-related macular degeneration: dry and wet. Here are the differences in symptoms, diagnosis and treatment for both types of this eye disease.

[See: 13 Foods That Do Your Eyes Good.]

Symptoms of Dry Versus Wet Age-Related Macular Degeneration

One key difference in dry versus wet age-related macular degeneration is the symptoms, which can vary in severity depending on the type you have.

In fact, if you have the dry, early form (also called mild age-related macular degeneration), you may not have any symptoms at all. An eye doctor would only know that you have age-related macular degeneration through a special exam.

However, if you have intermediate age-related macular degeneration, you likely will notice some vision changes, including:

-- Blurry vision.

-- Seeing black or dark areas in your central vision.

-- Vision that appears darker than before.

-- Trouble reading.

-- Difficulty seeing details in both close and far vision.

These same vision changes can appear if you have geographic atrophy, a form of dry age-related macular degeneration characterized by regions of the retina where dead cells appear, according to the BrightFocus Foundation. Vision loss happens gradually over time.

In contrast to the dry forms, quicker vision loss is the most noticeable symptom of wet age-related macular degeneration. In fact, 90% of the vision loss associated with age-related macular degeneration is associated with the wet form of the disease, Khurana says. "When people transition from intermediate to wet, they see distortions. It's like looking underwater," Rosenfeld describes. The growth of abnormal blood vessels below the retina is what eye doctors look for when identifying wet age-related macular degeneration. These vessels may begin to leak, which is why the advanced form of this disease got the name wet age-related macular degeneration.

Although wet age-related macular degeneration is associated with vision loss, you can usually save most of your vision if you catch it early enough.

If you have these vision-related symptoms, set an appointment with an eye doctor. You could have age-related macular degeneration, or you could have a cataract, which is a clouding of the lens that causes similar symptoms. Or you could also have both, "and the cataract just exacerbates the macular degeneration," Rosenfeld adds.

[See: When Contact Lenses Cause Vision Problems.]

Diagnosis of Dry Versus Wet Age-Related Macular Degeneration

Wet and dry age-related macular degeneration are diagnosed the same way. The biggest difference is what signs of disease that eye doctors find. First, doctors use a dilated eye exam. This involves using special drops to make your eyes widen, enabling the doctor to see the back of your eye. Dilated eye exams are used to help detect diseases like macular degeneration and glaucoma. During the dilated eye exam, your eye doctor will look for signs of disease you can't see or notice.

For dry macular degeneration, eye doctors look for yellow-colored deposits called drusen and deposits of pigment underneath the retina. However, for wet age-related macular degeneration, the exam will help detect abnormal blood vessel growth and blood vessels that leak fluid.

Eye doctors also will use special technology -- such as optical coherence tomography, or OCT, which uses light waves to get pictures of sections of the retina -- and a test called fluorescein angiogram. During this test, a fluorescent dye is injected in the arm, and pictures are taken as the colored dye passes through your eye's blood vessels, according to the National Eye Institute. This helps eye doctors see the leaking blood vessels that are part of wet age-related macular degeneration.

Treatments for Dry Versus Wet Age-Related Macular Degeneration

The treatments for dry versus wet age-related macular degeneration also can vary greatly. There's even one form of dry macular degeneration that doesn't have any treatments, although that may change in a few years.

If you have the mild, dry form of macular degeneration, your doctor may advise you only to return for regular monitoring, Rosenfeld says.

If you have dry age-related macular degeneration, particularly the intermediate form, your eye doctor may advise you to use an over-the-counter vitamin formulation called AREDS2, short for Age-Related Eye Disease Study 2. The vitamins contain high doses of lutein, zeaxanthin, zinc, copper and vitamins C and E. In clinical trials, the AREDS vitamins helped lower the chance of developing wet macular degeneration by about 25%.

"This reduces their risk, but it doesn't eliminate it," says Dr. Peter Campochiaro, a professor of ophthalmology and director of the Retinal Cell and Molecular Laboratory at Johns Hopkins University in Baltimore.

Rosenfeld has seen patients with the disease who started to use AREDS vitamins and then turned to younger family members to recommend that they use AREDS vitamins as well. "That's a mistake," he cautions. That's because there's no proof that using them will help prevent the disease if you don't already have it.

Unfortunately, there are no current treatments for the dry form of macular degeneration called geographic atrophy. That's why there are several studies underway to help find a treatment for this form of dry age-related macular degeneration. These potential treatments include special eye drops and cell transplantation, says Dr. Charles Wykoff of Retina Consultants Houston.

One example of a future treatment is a drug called APL-2, designed to target a protein called C3 that's part of our immune system's complement system. The complement system plays a role in causing age-related macular degeneration, according to the American Macular Degeneration Foundation. Phase 2 trial results from APL-2 included a 29% reduction in lesions, or areas of abnormal tissue, in the eye caused by geographic atrophy, according to a press release from drug maker Apellis Pharmaceuticals.

All of the treatments under investigation are still several years away from reaching the market, Campochiaro says.

[See: 11 Things Seniors Should Look for in a Health Provider.]

In contrast with the dry form, the wet form of age-related macular degeneration has several treatments available. The most common treatment for wet age-related macular degeneration is an injection of what is called an anti-vascular endothelial growth factor (VEGF) drug. These treatments have specific engineered proteins that block the activity of proteins that help build blood vessels, Wykoff says.

The injections can help lower the number of abnormal blood vessels in the retina and stop these blood vessels from leaking.

The two anti-VEGF injections currently approved by the U.S. Food and Drug Administration are ranibizumab (Lucentis) and aflibercept (Eylea). Bevacizumab (Avastin), a third treatment, also is used off-label in some patients, but is not approved by the FDA for age-related macular degeneration. (It's typically used for certain cancers.) Another anti-VEGF injection called brolucizumab has gone through phase 3 clinical trials and may be approved soon by the FDA.

The injections for wet age-related macular degeneration are made through the eye's vitreous cavity, a gel-filled area between the front of the eye and the retina. You'll receive special drops to not feel the injection, but you may feel a little pressure in the eye. "It's normal to feel stress about the first injection, but over time, patients get well adjusted to it," Rosenfeld says.

In 90% of patients, these injections stop your vision from getting worse, Khurana says. About a third of patients gain some of their vision back, especially when the injections first start. You have a greater chance of slowing disease progression and vision loss if your disease is detected earlier.

Most eye doctors will give these injections monthly to people with wet age-related macular degeneration until the disease slows down or stops. After that, the frequency is different for each person. Some return to the eye doctor's office for an injection once a month. Others can wait six or eight weeks between injections.

If you have wet age-related macular degeneration, try your best to show up for your scheduled injections. "We talk about this all the time with patients," Campochiaro says. "Life gets in the way. Patients break a leg, or a family member can't bring them. Yet each time they miss, there's the potential for scarring and permanent loss of vision."

Pharmaceutical companies have several studies underway for new therapies or new drug delivery approaches for wet age-related macular degeneration. This includes the use of a tiny reservoir, about the size of a grain of rice, that is placed in the eye and filled with a high concentration of the drug ranibizumab. A phase 2 trial found the reservoir was safe and as effective as monthly injections, according to a study published in the August 2019 issue of Ophthalmology. The phase 2 trial also found that 80% of patients went six months or longer without needing to return to the eye doctor, according to a press release from the company Genentech, which is making the reservoir. "That's a potential game-changer," Campochiaro says.

Other potential treatments include stem cell therapy and gene therapy. For instance, a therapy under development by Regenexbio called RGX314 uses what's called a viral vector to carry a gene into the cells of the retina. "That gene produces the protein that blocks VEGF continuously so injections are no longer needed," Campochiaro says. With this approach, you would only need a one-time treatment instead of regular injections. The company is currently enrolling for a phase 1/2a clinical trial.

Vanessa Caceres began writing for U.S. News in 2017, originally specializing in diabetes. She's a nationally published health, travel and food writer with an undergraduate degree in journalism and psychology from Hampshire College in Amherst, Massachusetts, and a graduate degree in linguistics/bilingual education from Georgetown University in Washington, D.C. In addition to U.S. News, Vanessa's health writing has been published with Everyday Health, Self, Newsday HealthLink, EyeWorld, The Rheumatologist and various other publications. She is a member of Business Networking International (BNI). Connect with her on Twitter at @FloridaCulture.